The insulin-like growth factor axis and plasma lipid levels in the elderly.
The activity of the hypothalamic-GH-insulin-like growth factor (IGF) network declines with age. It has recently been shown that increased cardiovascular mortality occurs in adults with GH deficiency. As hypercholesterolemia is common in GH-deficient adults, and because there is experimental evidence that GH may play a role in regulating plasma cholesterol, we decided to investigate the activity of the GH-IGF axis in an elderly population by measuring serum IGF-I, IGF-II, and IGF-binding protein-3 (IGFBP-3) levels and to study their relationship with blood lipid levels. One hundred and thirty-two elderly subjects, 52 men and 80 women, were studied (age range, 60-91 yr). Men had significantly lower levels of IGFBP-3, high density lipoprotein cholesterol (HDL-C) and apoprotein A1 (ApoA1) compared to the women, whereas IGF-I and IGF-II were only slightly lower. Using linear regression analysis, we observed an inverse relationship of age with IGF-I (r = -0.35; P < 0.001), IGF-II (r = 0.40; P < 0.001), IGFBP-3 (r = 0.52; P < 0.001), body mass index, and lipid levels. Univariate regression analysis showed a strong and positive correlation of both IGF-I and IGFBP-3 with HDL-C and ApoA1. Partial correlation analysis, after adjustment for age and body mass index, showed that IGFBP-3 and IGF-II were still significantly and positively related to HDL-C and ApoA1. Furthermore, a strong association was documented among IGF-I, IGF-II, and IGFBP-3. These data demonstrate that even in an elderly population, further aging is accompanied by a progressive decline in circulating IGF-I, IGF-II, and IGFBP-3, suggesting a continuing diminution of the GH-IGF axis throughout aging. Moreover, the strong correlation between HDL-C and an index of GH secretion, such as IGFBP-3, suggests that GH might play an important role in lipid metabolism in healthy elderly subjects.
Ceda
G P
GP
Cattedra di Geriatria, Università di Parma, Italy.
Dall'Aglio
E
E
Magnacavallo
A
A
Vargas
N
N
Fontana
V
V
Maggio
M
M
Valenti
G
G
Lee
P D
PD
Hintz
R L
RL
Hoffman
A R
AR
D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000097:blood*; D016632:Apolipoprotein A-I / Q000378:metabolism; D015992:Body Mass Index; D008076:Cholesterol, HDL / Q000097:blood; D005260:Female; D019382:Human Growth Hormone / Q000502:physiology; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000097:blood*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D007335:Insulin-Like Growth Factor II / Q000378:metabolism*; D008055:Lipids / Q000097:blood*; D008297:Male; D008875:Middle Aged; D012044:Regression Analysis; D012727:Sex Characteristics; D014280:Triglycerides / Q000097:blood
D016632:Apolipoprotein A-I; D008076:Cholesterol, HDL; D018972:Insulin-Like Growth Factor Binding Protein 3; D008055:Lipids; D014280:Triglycerides; D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II